Preparing and Adding Nodes

Preparing and Adding Nodes

Verify your new nodes are ready for integration into the existing Greenplum system.

To prepare new system nodes for expansion, install the Greenplum Database software binaries,
exchange the required SSH keys, and run performance tests.

Run performance tests first on the new nodes and then all nodes. Run
the tests on all nodes with the system offline so user activity does not distort results.

Generally, you should run performance tests when an administrator modifies node
networking or other special conditions in the system. For example, if you will run the
expanded system on two network clusters, run tests on each cluster.

Note: The Greenplum Database segment host naming convention is
sdwN where sdw is a prefix and N is an
integer. For example, on a Greenplum Database DCA system, segment host names would be
sdw1, sdw2 and so on. For hosts with multiple
interfaces, the convention is to append a dash (-) and number to the host
name. For example, sdw1-1 and sdw1-2 are the two interface
names for host sdw1.

To exchange SSH keys as root

Create a host file with the existing host names in your array and a
separate host file with the new expansion host names. For existing hosts, you can use
the same host file used to set up SSH keys in the system. In the files, list all hosts
(master, backup master, and segment hosts) with one name per line and no extra lines or
spaces. Exchange SSH keys using the configured host names for a given host if you use a
multi-NIC configuration. In this example, mdw is configured with a
single NIC, and sdw1, sdw2, and sdw3
are configured with 4
NICs:

To exchange SSH keys as the gpadmin user

gpssh-exkeys will check the remote hosts and perform
the key exchange between all hosts. Enter the gpadmin user password
when prompted. For
example:

***Enter password for gpadmin@hostname: <gpadmin_password>

Verifying OS Settings

Use the gpcheck utility to verify all new hosts in your array have the
correct OS settings to run Greenplum Database software.

To run gpcheck

Log in on the master host as the user who will run your Greenplum
Database system (for example,
gpadmin).

$ su - gpadmin

Run the gpcheck utility using your host file for new
hosts. For example:

$ gpcheck -f new_hosts_file

Validating Disk I/O and Memory Bandwidth

Use the gpcheckperf utility to test disk I/O and memory bandwidth.

To run gpcheckperf

Run the gpcheckperf utility using the host file for new
hosts. Use the -d option to specify the file systems you want to test
on each host. You must have write access to these directories. For
example:

$ gpcheckperf -f new_hosts_file -d /data1 -d /data2 -v

The utility may take a long time to perform the tests because it is
copying very large files between the hosts. When it is finished, you will see the
summary results for the Disk Write, Disk Read, and Stream tests.

For a network divided into subnets, repeat this procedure with a separate host file for
each subnet.

Integrating New Hardware into the System

Before initializing the system with the new segments, shut down the system with
gpstop to prevent user activity from skewing performance test results.
Then, repeat the performance tests using host files that include all nodes, existing
and new: